2024-2025 La Nina

[snowman19]

@Bluewave

[so_whats_happening]

23 hours ago, snowman19 said:

@Gawx @bluewave  @40/70 Benchmark @donsutherland1
 

Wait wait so CDAS is ok to use now?

[bluewave]

43 minutes ago, snowman19 said:

@Bluewave
 

Yeah, Canada is finally expected to begin cooling off from all the recent record warmth at least in the western and central regions.

 

 

 

[snowman19]

Yeah, Canada is finally expected to cool off a bit from all the recent record warmth at least in the western and central regions.



 
 
 

EPS and GEFS are identical now for the 1/20 period. The pattern shift begins just after mid-month

[bluewave]

19 minutes ago, snowman19 said:

EPS and GEFS are identical now for the 1/20 period. The pattern shift begins just after mid-month

 

 

 

 

Perhaps a better overrunning scenario across the Northern Tier as we will finally see colder air nearby in Canada instead of all the warmth we have been getting. The other nuances to the pattern will be how much AO blocking remains. Plus can we maintain some hint of ridging near the Baja instead of a trough which has been so frequent in recent years with -PNAs? 

[michsnowfreak]

Welcoming a pattern shift, a more active northern stream, and a more traditional Nina with OPEN ARMS. Im sure many other of my fellow northern posters are as well. In the last 40 days, Detroit has seen snowflakes fall on 25 of the 40 days, totaling 5.8". This is what a cold/dry pattern gives you in the southern Lakes outside the snowbelt. 

[LakePaste25]

That 12z euro run spelled trouble for good snow storm chances as it buries vort after vort in the southwest. It is probably the more extreme scenario, however. 

[Allsnow]

 

[Allsnow]

3 hours ago, snowman19 said:

EPS and GEFS are identical now for the 1/20 period. The pattern shift begins just after mid-month

 

 

 

 

EPS at 12z do not agree with the gefs 

[snowman19]

15 minutes ago, Allsnow said:

EPS at 12z do not agree with the gefs 

 

15 minutes ago, Allsnow said:

EPS at 12z do not agree with the gefs 

We’ll see but the tropical forcing progression after 1/18 supports -PNA

[MJO812]

1 minute ago, snowman19 said:

 

We’ll see but the tropical forcing progression after 1/18 supports -PNA

That's not a bad thing with blocking.

[bluewave]

1 hour ago, Allsnow said:

 

Maybe the best -EPO of the winter so far if we can get some coupling with the strat.

 

[LakePaste25]

4 hours ago, bluewave said:

Perhaps a better overrunning scenario across the Northern Tier as we will finally see colder air nearby in Canada instead of all the warmth we have been getting. The other nuances to the pattern will be how much AO blocking remains. Plus can we maintain some hint of ridging near the Baja instead of a trough which has been so frequent in recent years with -PNAs? 

If we can maintain some Baja ridging, we can hope for a more February 2014 look, as opposed to recent february’s. 

 

[GaWx]

Today’s Euro Weekly for 1/20-6 once again has cold dominating much of the US (especially N Rockies to MidAtlantic) though this continues to be the final week of the cold week streak (that includes the 2 weeks prior) before the long advertised change to much warmer:

 

[Allsnow]

34 minutes ago, bluewave said:

Maybe the best -EPO of the winter so far if we can get some coupling with the strat.

 

Yeah, looks like the coldest air of the winter coming if true 

[GaWx]

11 minutes ago, Allsnow said:

Yeah, looks like the coldest air of the winter coming if true 

But even if so, that coldest may not include much of the S US, at least in the means as we’re going to be quite cold these next 2 weeks it appears.

[bluewave]

25 minutes ago, Allsnow said:

Yeah, looks like the coldest air of the winter coming if true 

Yeah, it will be interesting to see how low we can get the winter cold departure by January 25th. The EPS and GEFS weeklies want to bring in a milder pattern by the end of January into February. So the winter negative temperature departures around our area may get smaller as February progresses. Having a cold enough departure by then may raise the possibility of our first colder winter here in 10 years. Even if it’s strictly a function of the warmer 91-20 climo and could be warmer than normal against the old 81-10 normals. But you never know for sure since we have seen several late winter La Niña periods overperform expectations and boost the winters above average based on how mild the finish was. Getting 9 warmer winters in a row is so statistically rare that you would think that one of these years we would get a break even if only by a small margin.

[so_whats_happening]

3 hours ago, Allsnow said:

Yeah, looks like the coldest air of the winter coming if true 

Within 240 hours now is usually my go to for a strong possibility of this occurring especially with it being the stratosphere not a whole lot of fluctuation happens at that layer within 5-7 days. 10 days you can get some minor changes in position and intensity but this is looking promising. This would throw ideas of a really warm February off a bit considering the connection of strat to 500mb.

[PhiEaglesfan712]

13 hours ago, bluewave said:

Yeah, it will be interesting to see how low we can get the winter cold departure by January 25th. The EPS and GEFS weeklies want to bring in a milder pattern by the end of January into February. So the winter negative temperature departures around our area may get smaller as February progresses. Having a cold enough departure by then may raise the possibility of our first colder winter here in 10 years. Even if it’s strictly a function of the warmer 91-20 climo and could be warmer than normal against the old 81-10 normals. But you never know for sure since we have seen several late winter La Niña periods overperform expectations and boost the winters above average based on how mild the finish was. Getting 9 warmer winters in a row is so statistically rare that you would think that one of these years we would get a break even if only by a small margin.

I feel like this is going to come down to the wire, like the summer of 2023, which held off by one-tenth of a degree to officially finish with the first below average summer since 2014 (and breaking the 8-year streak of above average summers) before torching the first week of September. I feel like February will be close to average, and we're going to get a torch during the first week of March.

[bluewave]

On 1/5/2025 at 1:36 PM, GaWx said:

The Dec 2024 PNA came in at +1.70, setting a new record high PNA for a non-El Nino (going back to 1950) beating the +1.58 of 2020. The only Dec PNAs higher than 2024 were during El Niño:

2006 +1.86

1969 +1.84

1963 +1.77
 

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

Back in October I was pointing out the potential PNA mismatch signal for December which worked out. But I also mentioned that other factors weren’t lining up like they did as recently as 2020 and 2017.  As it turns out the Northern Stream of the Pacific was among the strongest we have ever seen with such a positive +PNA. So this lead to the warmer and less snowy outcome than most of the past +PNA La Niña Decembers.

La Niña Decembers with strong +PNA patterns

2024…PNA…+1.70….NYC….avg temp…38.2°….snowfall…2.8”

2020…+1.58….39.2°….10.5”

2017….+0.89…35.0°…..7.7”

2005…+1.38….35.3…..9.7”

2000….+1.23…31.1°…..13.4”

1995…..+0.92…32.4°….11.5”

1985…..+1.39….34.2°….0.9”

1963……+1.77….31.2°….11.3”

 

[snowman19]

@Bluewave Not surprisingly the EPS is right back to showing a -PNA just after mid-month

[snowman19]

3 minutes ago, bluewave said:

My guess is that the -PNA Arctic airmass at its core will more impressive than the cold we are getting with the +PNA since Canada will get much colder. 

Yea, -EPO driven. Besides the RNA, also looks like a flip to -AAM and a strong SPV/+AO

[GaWx]

Today’s Euro weeklies are still full steam ahead fwiw for -PNA/SE ridge in the first half of Feb.

[donsutherland1]

Will Atlanta See Measurable Snowfall Late This Week?

The ensembles show an energetic trough swinging out of Texas Friday morning. The trough and ridge on the West Coast have some similarities to those features on January 21, 1987 when a storm dumped 3.6" of snow on Atlanta and 7.1" at Athens. The forecast air mass is expected to be reasonably similar to that in 1987. Therefore, I suspect that both cities will see measurable snowfall on Friday into Saturday, although I don't believe this storm will rival the 1987 one. A coating to an inch with some locally higher amounts seems reasonable at this time.

Atlanta's Measurable Snow Events Since 2015:
January 22-23, 2016: 0.3"
December 8-9, 2017: 2.3"
January 16-17, 2018: 2.4"
January 16, 2022: 0.3"
January 28, 2022: 0.2"
December 26, 2022: 0.1"

Athens' Measurable Snow Events Since 2015:
January 23, 2016: 0.1"
January 17 2018: 1.1"
February 8, 2020: 0.5"
January 16, 2022: 1.8"
January 21, 2022: 0.2"

 

[GaWx]

32 minutes ago, donsutherland1 said:

Will Atlanta See Measurable Snowfall Late This Week?

The ensembles show an energetic trough swinging out of Texas Friday morning. The trough and ridge on the West Coast have some similarities to those features on January 21, 1987 when a storm dumped 3.6" of snow on Atlanta and 7.1" at Athens. The forecast air mass is expected to be reasonably similar to that in 1987. Therefore, I suspect that both cities will see measurable snowfall on Friday into Saturday, although I don't believe this storm will rival the 1987 one. A coating to an inch with some locally higher amounts seems reasonable at this time.

Atlanta's Measurable Snow Events Since 2015:
January 22-23, 2016: 0.3"
December 8-9, 2017: 2.3"
January 16-17, 2018: 2.4"
January 16, 2022: 0.3"
January 28, 2022: 0.2"
December 26, 2022: 0.1"

Athens' Measurable Snow Events Since 2015:
January 23, 2016: 0.1"
January 17 2018: 1.1"
February 8, 2020: 0.5"
January 16, 2022: 1.8"
January 21, 2022: 0.2"

 

I was there for the 1/21/87 ATL snow. It had no sleet or ZR on the borderline. Instead it was heavy snow in most areas but heavy rain (with possibly some flooding) just to the SE.

 This one looks different due to potential significant ice in possibly a wide region in the transition. The latest CMC and NAM say mainly ZR ATL.

[mitchnick]

Fyi, Cyclonicwx.com now has subsurface maps to the right of the Oisst link. 

https://cyclonicwx.com/sst.php

[George001]

6 hours ago, snowman19 said:

@Bluewave Not surprisingly the EPS is right back to showing a -PNA just after mid-month
 

 

 

 

 

 

 

 

 

Bring it on. Need something to shift the storm track north.